Dichloromethane water miscibility

This technique is used to extract effectively analytes that are polar in nature and strongly bound to soil. Typically, a solvent mixture containing a water-miscible solvent and an apolar solvent (e.g. methanol-dichloromethane) is used. A small aliquot of soil (10-30 g) is dried by mixing with sodium sulfate and refluxed for 8-16h to extract the residues. 

V-Fluorobis(phenylsulfonyl)amine (1 a) can be synthesized in a one-step reaction using commercially available bis(phenylsulfonyl)amine (up to 0.2 mol) and fluorine (10% F2/N2,1 equiv) in the presence of powdered sodium fluoride, either in acetonitrile at — 40 °C in an ambient pressure reactor131 or in trichlorofluoromethane/chloroform, water or a water-miscible organic solvent.133 iV-Fluorobis(phenylsulfonyl)amine (la) is soluble in most organic solvents, e.g. diethyl ether, tetrahydrofuran, dichloromethane. acetonitrile and toluene.131 133... 

When a water-miscible organic solvent such as ethanol (95%), glycol, or mixtures of ethanol and dichloromethane are used, the hypromellose should first be dispersed into the organic solvent, at a ratio of 5-8 parts of solvent to 1 part of hypromellose. Cold water is then added to produce the required volume. 

Sometimes the mutual solubility of a solvent pair of interest can easily be decreased by adding a third component. For example, it is common practice to add water to a solvent system containing a water-miscible organic solvent (the polar phase) and a hydrophobic organic solvent (the nonpolar phase). A typical example is the solvent system (methanol + water) + dichloromethane. An anhydrous mixture of methanol and dichloromethane is completely miscible, but adding water causes phase splitting. Adjusting the amount of water added to the polar phase also may be used to alter the K values for the extraction, density difference, and interfacial tension. Table 15-5 lists some common examples of solvent systems of this type. These systems are common candidates for fractional extractions. 

Solvents commonly used in normal phase chromatography are aliphatic hydrocarbons, such as hexane and heptane, halogenated hydrocarbons (e.g., chloroform and dichloromethane), and oxygenated solvents such as diethyl ether, ethyl acetate, and butyl acetate. More polar mobile phase additives such as isopropanol, acetone, and methanol are frequently used see Table 2). The technique is particularly suited to analytes that are very hydrophobic, e.g., fat-soluble vitamins such as tocopherols (6J and other hydrocarbon-rich metabolites that exhibit poor solubility in the water-miscible solvents employed in other separation modes. In addition, since the geometry of the polar adsorbent surface is fixed, the technique is useful for the separation of positional isomers the proximity of functional groups to the adsorbent surface, and hence the strength of interaction, may well differ between isomers. 

LLE is a widely used technique among the official US-EPA methods for the preconcentration of pesticides in liquid samples. Nonpolar solvents for the LLE of pesticides include w-hexane, benzene, and ethyl acetate. Water-miscible solvents for this purpose include dichloromethane, methanol, acetonitrile, acetone, and water, which have been employed for the extraction of residues from high-moisture commodities. Mixed solvents have often been used to finely adjust the solvent strength. Thus, various carbamate pesticides were extracted from aqueous environmental samples with chloroform and determined by HPLC with a mean recovery of 71 Also, a method based on the extraction by sonication of solid samples placed in small columns with a low volume of ethyl acetate was developed for the extraction of thiocarbamates and other herbicides from soil with recoveries between 89 and 109%. ... 

Wastes, non-water miscible Extract with dichloromethane followed by cleanup EPA 8410 GC/FT-IR 10 pg/L No data EPA 1994b O > 1 ... 

Wastes, non-water miscible EPA Extraction Methods 3510 or 3520 using dichloromethane followed by cleanup EPA 8270 GC/FT-IR 50 mg/kg 76% EPA 19981 ... 

Due to their coordinating properties, halide impurities can have disastrous effects on metal-catalyzed reactions, so special attention has to be given to the control of halide in ILs when they are obtained in a two-step synthesis. Halide impurities can be effectively removed from hydrophobic ILs by simply washing them several times with water. The preparahon of water miscible ILs is a more demanding process the IL can be dissolved in dichloromethane and washed with successive small portions of deionized water. However, this method results in a lowering of the yield and cannot be applied for the most hydrophilic ILs. In the latter case, the direct alkylation of N-alkyl imidazole should be preferred. 

Twenty-five ecdysteroids, derived irom 20-hydroxyecdysone, were studied in both normal-phase (silica column) and reversed-phase (Cig column) modes. IPA/dichloromethane/water (30/125/2), IPA/cyclohexane/water (40/400/3), or IPA/iso-octane/water (30/100/2) was selected as NP mobile phase. Here is an instance where the water concentration in a immiscible matrix (e.g., iso-octane) is increased due to the presence of a mutually miscible solvent, IPA. Methanol/water (50/50), ethanol/water (30/70), or IPA/water (18/72), all containing 0.1% TEA, were studied as reversed-phase mobile phases [423]. Methanol proved particularly effective in the RP separation of analytes that varied by the degree of unsaturation (i.e., number of double bonds). IPA, as a RP solvent, was superior in resolving 5a-5jS pairs. IPA was extremely effective in the separation of 20-hydroxyecdysone and polypodine B mixtures. These results are not surprising since ecdysones are polyhydroxylated. 

An ammonia diffusion system is applicable to amphoteric drug substances. In this method, the mixture of three partially immiscible solvent i.e. acetone, ammonia water, dichloromethane was used as crystallization system. In this system ammonia water acted as bridging liquid as well as good solvent, acetone as the water miscible but poor solvent, thus drug precipitated by solvent change without forming ammonium salt. Water immiscible solvent such as hydrocarbon or halogenated hydrocarbons e.g. dichloromethane induced liberation of ammonia water. 

Particulate matter, obtained from the filtration process, can be analyzed with the same analytical methods normally used for sediment samples. Solvents used in the filter extraction are generally the same as those previously described for liquid-liquid extraction (i.e., -hexane [152], toluene [31], and pentane/mefhylene chloride (2 1) [85]). However, water-miscible solvents can also be used such as acetone, ethyl acetate and methanol (n-heptane/acetone (1 1) [67], hexane/acetone (3 2) [10], dichloromethane/methanol (2 1) [46], and dichloromethane/methanol (2 1) [135]). The extraction process is carried out in a Soxhlet extractor or, more simply, in an ultrasonic bath— this improves the exchange process between the particle surface and the bulk of the organic solution. Pressurized liquid extractions (accelerate solvent extraction) can be used for a more efficient extraction, above all in terms of extraction times [10,67]. 

The oxidation of organic compounds by water-soluble inorganic oxidants is often made difficult not only by the insolubility of the organic substrate in water, but also by the susceptibility of many of the miscible non-aqueous solvents to oxidation. Solubilization of the ionic oxidant into solvents such as benzene, chloroform, dichloromethane or 1,2-dichlorobenzene, by phase-transfer catalysts obviates these problems, although it has been suggested that dichloromethane should not be used, as it is also susceptible to oxidation [1]. 

For many years, prior to the development of current phase-transfer catalytic techniques, tetraalkylammonium borohydrides have been used in non-hydroxylic solvents [see, e.g. I, 2], Originally, the quaternary ammonium borohydrides were obtained by metathesis in water or an alcohol [3, 4], However, with greater knowledge of the phase-transfer phenomenon, an improved procedure has been developed in which the ammonium salt is transferred into, and subsequently isolated from, dichloromethane [5, 6], In principle, it should be possible to transfer the quaternary ammonium borohydride for use in any non-miscible organic solvent. It should be noted, however, that quaternary ammonium cations are susceptible to hydrogeno-lysis by sodium borohydride in dipolar aprotic solvents to yield tertiary amines [4]. 

Solubility-. Slightly soluble in water (0.8 mg/L at 24°C) miscible with carbon tetrachloride, chloroform and dichloromethane (Verschueren, 1996 United States National Library of Medicine, 1997)... 

David. A. Franz and David Speckhard, "Densities and Miscibilities of Liquids and Liquid Mixtures," /. Chem. Educ., ol. 68, 1991, 594. Using a graduated cylinder and electronic balance, the densities of water, dichloromethane, and petroleum ether are determined. A heavier mass of water is shown to form a layer on top of the more dense dichloromethane, but below the less dense petroleum ether. Mixtures of the miscible organic solvents are prepared with average densities above or below the density of water. 

Synonyms dichloromethane Formula CH2C12 MW 84.94 CAS [75-09-2] a volatile halogenated hydrocarbon widely used as a solvent boils at 40°C vapor pressure 349 torr at 20°C density 1.323 g/mL at 20°C solubility in water, very low (1.3%) miscible in organic solvents nonflammable. 

Reference Electrodes for Use in Nonpolar Solvents. Solvents such as dichloromethane (not highly polar) present special problems. Their low dielectric constants promote extensive ion association, and cell resistances tend to be large. For this reason they are often used in mixtures with more polar solvents. Because dichloromethane and other nonpolar solvents are not miscible with water, use of an aqueous reference electrode with such solvents is not practical unless a salt bridge with some mutually miscible solvent is used. A better approach is to use a reference electrode of known reliability prepared in a solvent miscible with dichloromethane or to use the reference electrode based on the half-cell in dichloromethane.88... 

An investigation into the co-solvent employed was also carried out [21]. The solvents were selected so that they differed significantly in dielectric constant (fi, indicated by the values in parentheses) dichloromethane (8.9), trifluoroethanol (26.7), acetonitrile (37.5), water (78.4) and formamide (111). The epoxidation of 1-phenylcyclohexene with catalyst (17) was tested using these co-solvents with water in a 1 1 ratio. Epoxidation did not occur in dichloromethane this is perhaps due to the poor miscibility of the two solvents, thus limiting the availability of the inorganic oxidant in the organic phase. No reaction was also observed in formamide. This could be due to the iminium species being too well stabilized/solvated, and the possibility of an irreversible attack by the formamide cannot be dismissed. In trifluoroethanol, the reaction had a similar profile to that in acetonitrile both reactions were complete in 30 min, but the ee was somewhat lower (26% ee in trifluoroethanol and 40% ee in acetonitrile). 

BTF is not miscible with water and hence, it can be used for extraction purposes. Like dichloromethane, it is heavier than water. We observed, however, that phase separation between water and BTF is sometimes difficult. BTF can be used as solvent for chromatography as well. However, it has a typical intense aromatic odor, which is not convenient when using large quantities. In addition,because of the high boiling point, the solvent removal process is relatively slow (compared to solvents like ether and dichoromethane) and loss of relatively volatile products can occur. Because of these practical disadvantages, we have limited the use of BTF as a chromatography solvent to the purification of fluorous compounds (see 4.0). 

Herbicides are components with relatively low Kow values and high solubilities. This means that they can be extracted from soil with a water/acetone mixture. To enable the measurement of low concentrations, the herbicides have to be transferred to a volatile solvent, which is not miscible with water, like petroleum ether or dichloromethane. If the original acetone/water extraction medium is concentrated (evaporation), the water percentage will increase during the concentration and the extracted components will precipitate or adsorb to the equipment. It is therefore necessary to add a solvent like petroleum ether to the system. There will be a distribution between the soil and the acetone/water mixture and one between the acetone/water mixture and the petroleum ether. If the water content is low the system is very effective for non-polar components. With a higher water content it will be more effective for more polar components. With a too high water content the accessibility increasing properties of acetone are lost and the efficiency of the extraction process decreases. 

Dichloromethane [75-09-2] (methylene chloride) is a colorless, highly volatile, neutral liquid with a characteristic odor. It is insoluble in water but miscible with organic solvents. It has a very good solvency for many organic substances, such as fats, oils, waxes, and resins. Bitumen, rubber, chlorinated rubber, polystyrene, postchlorinated poly(vinyl chloride), vinyl chloride copolymers, polyacrylates, and cellulose esters are also soluble. The solubility spectrum can be expanded by adding other solvents. A mixture of methanol or ethanol and dichloromethane is a good solvent for cellulose ethers and acetyl cellulose. Cellulose nitrate is, however, insoluble. 

---